To exercise at or near capacity is the best way I know of reaching a true introspective state. If you do it right, it can open all kinds of inner doors.

Advertising Disclosure: Please note that many links to retailers are affiliate links, which yields a commission for us. allauthor.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon sites.